1. Field of the Invention
The present invention relates to a multiple-beam electronic scanning antenna. It can be applied especially to uniquely phase-controlled antennas for example in the context of satellite or terrestrial communications requiring simultaneous communications with several variable sites.
2. Discussion of the Background
Telecommunication requirements are constantly on the increase. Furthermore, military, civilian, professional and private users are demanding ever lower costs. To meet these demands, telecommunication equipment has to be very economical. To this end, it is worthwhile to use multiple-beam antennas which enable simultaneous transmission and reception in several different directions which, furthermore, are not fixed in advance. Thus, it is advantageous for a communications satellite to be capable of communicating simultaneously, by means of one and the same antenna, with several stations that are variable in number and position. This is also the case with terrestrial radiocommunications for example where several mobile sites belonging to one and the same network can communicate with one another simultaneously.
There are known ways of making multiple-beam electronic scanning antennas, but these antennas are active, i.e. they comprise not just phase-shifters but active modules that can be controlled in phase but also in amplitude modulation, more particularly in modulation of the power emitted per module. Now, an active module antenna is costly.